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Date: Fri, 16 Nov 2007 09:57:43 -0800 (PST)
From: "Martin Sebor (JIRA)" <jira@apache.org>
To: stdcxx-dev@incubator.apache.org
Subject: [jira] Commented: (STDCXX-226) __rw::__rw_new_capacity() uses
 floating point math
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    [ https://issues.apache.org/jira/browse/STDCXX-226?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12543151 ] 

Martin Sebor commented on STDCXX-226:
-------------------------------------

I'm concerned about the performance implications of replacing a single floating point multiplication with three integer divisions, two multiplications, and an addition. Isn't there a way to compute the same (or similar) result using a less expensive formula (ideally using just multiplication and shift).

> __rw::__rw_new_capacity() uses floating point math
> --------------------------------------------------
>
>                 Key: STDCXX-226
>                 URL: https://issues.apache.org/jira/browse/STDCXX-226
>             Project: C++ Standard Library
>          Issue Type: Improvement
>          Components: 23. Containers
>    Affects Versions: 4.1.2, 4.1.3
>         Environment: all
>            Reporter: Martin Sebor
>            Assignee: Farid Zaripov
>         Attachments: new_capacity.patch
>
>
> Moved from the Rogue Wave bug tracking database:
> ****Created By: sebor @ May 09, 2002 11:15:41 AM****
> The template __rw_new_capacity() uses floating point arithmetic which may be less efficient than integer arithmetic on some architectures. Need to change to integer arithmetic and correctly handle integer overflow.

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